Fix csrf (#2126)

* apply fix

* Fixes empty th:action

* Update build.gradle

* fix

* formatting

---------

Co-authored-by: Dimitrios Kaitantzidis <james_k23@hotmail.gr>

src/main/resources/templates/security/sanitize-pdf.html

@@ -16,7 +16,7 @@
                 <span class="material-symbols-rounded tool-header-icon security">sanitizer</span>
                 <span class="tool-header-text" th:text="#{sanitizePDF.header}"></span>
               </div>
-              <form action="api/v1/security/sanitize-pdf" method="post" enctype="multipart/form-data">
+              <form th:action="@{'api/v1/security/sanitize-pdf'}" method="post" enctype="multipart/form-data">
                 <div class="mb-3">
                   <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multipleInputsForSingleRequest=false, accept='application/pdf')}"></div>
                 </div>